1918513621 has 4 divisors (see below), whose sum is σ = 1920851244. Its totient is φ = 1916176000.

The previous prime is 1918513607. The next prime is 1918513717. The reversal of 1918513621 is 1263158191.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 197093521 + 1721420100 = 14039^2 + 41490^2 .

It is a cyclic number.

It is not a de Polignac number, because 1918513621 - 2⁹ = 1918513109 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1918513601) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1167580 + ... + 1169221.

It is an arithmetic number, because the mean of its divisors is an integer number (480212811).

Almost surely, 2^1918513621 is an apocalyptic number.

It is an amenable number.

1918513621 is a deficient number, since it is larger than the sum of its proper divisors (2337623).

1918513621 is an equidigital number, since it uses as much as digits as its factorization.

1918513621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2337622.

The product of its digits is 12960, while the sum is 37.

The square root of 1918513621 is about 43800.8404143117. The cubic root of 1918513621 is about 1242.5721886679.

It can be divided in two parts, 1918 and 513621, that multiplied together give a triangular number (985125078 = T₄₄₃₈₇).

The spelling of 1918513621 in words is "one billion, nine hundred eighteen million, five hundred thirteen thousand, six hundred twenty-one".